COROT-9b
Encyclopedia
COROT-9b is an exoplanet orbiting the star
COROT-9, approximately 1500 light years away in the constellation Serpens
. COROT-9b's distance of nearest approach to its parent star of approximately 0.36 AU is the largest of all known transiting planets, with an orbital period of 95 days. The transit of this planet lasts 8 hours. The planet is at a distance from its star where there is a strong increase in albedo
as the temperature decreases, because of the condensation of reflective water clouds in the atmosphere. This suggests its atmosphere may be locked into one of two states: a cloudless state with temperatures between 380 K and 430 K, or covered in water clouds with a temperature in the range 250 K to 290 K.
satellite,, which looks for a small dip in starlight as a planet passes in front of its parent star, and the ESO
HARPS instrument. This discovery was announced in 2010 on St. Patrick's Day, after 145 days of continuous observations in summer 2008.
of 0.84 times that of Jupiter (MJ
) as determined from HARPS spectroscopy, and has a radius
of 1.05 times that of Jupiter (RJ) as determined from photometry
of the transit light curve. This implies that this planet has a density
of 96% that of water, and surface gravity 1.93 times that of Earth.
and helium
(like Jupiter
and Saturn
), with up to 20 Earth masses of other elements including water, as well as and rock at high temperatures and pressures. The authors of the COROT-9b discovery paper refer to the planet as a class II ("water cloud") or class III ("clear") atmosphere planet, as described by the Sudarsky extrasolar planet classification.
Star
A star is a massive, luminous sphere of plasma held together by gravity. At the end of its lifetime, a star can also contain a proportion of degenerate matter. The nearest star to Earth is the Sun, which is the source of most of the energy on Earth...
COROT-9, approximately 1500 light years away in the constellation Serpens
Serpens
Serpens is a constellation of the northern hemisphere. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy and it remains one of the 88 modern constellations defined by the International Astronomical Union....
. COROT-9b's distance of nearest approach to its parent star of approximately 0.36 AU is the largest of all known transiting planets, with an orbital period of 95 days. The transit of this planet lasts 8 hours. The planet is at a distance from its star where there is a strong increase in albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
as the temperature decreases, because of the condensation of reflective water clouds in the atmosphere. This suggests its atmosphere may be locked into one of two states: a cloudless state with temperatures between 380 K and 430 K, or covered in water clouds with a temperature in the range 250 K to 290 K.
Discovery
COROT-9b was discovered by combining observations from the CoRoTCorot
Corot may refer to:* Jean-Baptiste-Camille Corot, French landscape painter * COROT, a space mission with the dual aims of finding extrasolar planets and performing asteroseismology* COROT-7, a dwarf star in the Monoceros constellation...
satellite,, which looks for a small dip in starlight as a planet passes in front of its parent star, and the ESO
ESO
ESO, as a three-letter abbreviation, may stand for:* European Southern Observatory* Ensemble Studios Online* English Symphony Orchestra* Edmonton Symphony Orchestra* Executive Stock Options...
HARPS instrument. This discovery was announced in 2010 on St. Patrick's Day, after 145 days of continuous observations in summer 2008.
Mass and size
COROT-9b has a massMass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
of 0.84 times that of Jupiter (MJ
Jupiter mass
Jupiter mass , is the unit of mass equal to the total mass of the planet Jupiter . Jupiter mass is used to describe masses of the gas giants, such as the outer planets and extrasolar planets. It is also used in describing brown dwarfs....
) as determined from HARPS spectroscopy, and has a radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
of 1.05 times that of Jupiter (RJ) as determined from photometry
Photometry (astronomy)
Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation...
of the transit light curve. This implies that this planet has a density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
of 96% that of water, and surface gravity 1.93 times that of Earth.
Atmosphere and interior
Since COROT-9b is the first temperate giant exoplanet found by the transit method, astronomers will be able to study the atmosphere of a temperate giant planet for the first time, examining the composition of clouds, the composition of the atmosphere, temperature distributions, and even some details of the interior of the planet. The atmosphere of this planet is presumably dominated by hydrogenHydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
and helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
(like Jupiter
Jupiter
Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn,...
and Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
), with up to 20 Earth masses of other elements including water, as well as and rock at high temperatures and pressures. The authors of the COROT-9b discovery paper refer to the planet as a class II ("water cloud") or class III ("clear") atmosphere planet, as described by the Sudarsky extrasolar planet classification.
See also
- COROTCorotCorot may refer to:* Jean-Baptiste-Camille Corot, French landscape painter * COROT, a space mission with the dual aims of finding extrasolar planets and performing asteroseismology* COROT-7, a dwarf star in the Monoceros constellation...
is a CNESCNESThe is the French government space agency . Established under President Charles de Gaulle in 1961, its headquarters are located in central Paris and it is under the supervision of the French Ministries of Defence and Research...
space mission to discover planets using the photometric transit method. It is in polar orbitPolar orbitA polar orbit is an orbit in which a satellite passes above or nearly above both poles of the body being orbited on each revolution. It therefore has an inclination of 90 degrees to the equator...
around the Earth. - COROT-7b is a rocky super-EarthSuper-EarthA super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's gas giants. The term super-Earth refers only to the mass of the planet, and does not imply anything about the surface conditions or habitability...
. - HD 80606 bHD 80606 bHD 80606 b is a superjovian planet 190 light-years distant in the constellation of Ursa Major. The planet was discovered orbiting the star Struve 1341 B in April 2001 by a team led by Michel Mayor and Didier Queloz. Based on its mass, at 4 times that of Jupiter, it is a gas giant...
is the longest period (but much more eccentric than CoRoT-9b) transiting planet. - GJ 1214 b is a transiting super-Earth found by MEarth ProjectMEarth ProjectThe MEarth Project is a United States NSF-funded, robotic observatory that is part of Fred Lawrence Whipple Observatory on Mt. Hopkins, Arizona, USA. The project monitors the brightness of thousands of red dwarf stars with the goal of finding transiting planets...
.
External links
- "CoRoT-9b, a temperate exoplanet" - DLR Portal, 2010.march.17